DiffuseIndirect_Lumen_3 parameter missing and causing crash with Screen Space reflections and Lumen Async Compute

UE - Graphics Features - Lumen - May 3, 2025

When the Reflection Method is set to Screen Space and Lumen reflections async compute is enabled Unreal will crash because DiffuseIndirect_Lumen_3 parameter missing, due to how DenoiserOutputs are o ...

Crash when changing window resolution with AMD GPU, D3D11 and renderoffscreen

UE - Rendering Architecture - RHI - Apr 9, 2025

Context A crash can be induced with running Unreal Engine with DirectX11, a AMD GPU and running -renderoffscreen flag, and the main window is resized. This issue was first observed with the PixelStre ...

Clay Render mode is not working with Modeling tools/Faces.

TM - Interoperability - Mar 10, 2025

[Image Removed] The Clay material is quite useful when the user needs to manipulate objects that originally has transparent materials, so not being able to use this feature on faces mode feels li ...

FHLSLMaterialTranslator::GetMaterialEnvironment can crash or not load UMaterialParameterCollections

UE - Rendering Architecture - Materials - Apr 30, 2025

In UE 5.5, the Editor may crash in FHLSLMaterialTranslator::GetMaterialEnvironment when loading materials with Material Parameter Collections, likely due to async loading. Calling ParameterCollectio ...

VisionOS deferred renderer regression

UE - Platform - XR - Sep 11, 2024

Deferred desktop renderer does not function correctly on visionOS.  It did work in 5.4.  One problem is the r.XRMSAAMode setting forcing 4 samples even when not using msaa, but there are other probl ...

Creating a GeometryCollectionActor from a GeometryCollectionAsset is ignoring some of the data set in the asset

UE - Simulation - Physics - Mar 13, 2025

When you create a GeometryCollectionActor by dragging a GeometryCollectionAsset from the ContentBrowser into the scene, instead of using the PhysicsMaterial defined in the GeometryCollectionAsset, i ...

Physics Constraint Component loss of accuracy

UE - Simulation - Physics - Mar 6, 2025

Physics Constraint Component has lost accuracy between Unreal versions 5.2 and 5.4 (and up). When measuring the exact distance between rigid bodies constrained by a Physics Constraint Component, the ...

[MetaSounds][Audio Bus] - MetaSound Sources using Audio Bus nodes spam underruns when Audio Mixer Sample Rate is less or greater than 48kHz

UE - Audio - Audio Bus - Oct 5, 2023

Setting the Audio Mixer Sample Rate to 32000kHz causes underrun spam in audio bus reader and writer nodes and sounds to playback jittery. Tested with 24kHz and 32kHz. Does not repro in //Fortnite/R ...

Calling UBlueprintMapLibrary::GenericMap_Find with a non-existent key causes a memory leak

UE - Framework - Blueprint - Apr 15, 2025

When Calling UBlueprintMapLibrary::GenericMap_Find with a non-existent key, the function construct the default structure in-place on the given pointer without destroying the object. This behavior ca ...

Duplicated TextureLoadVirtualPageTable in GetCustomData functions in generated HLSL add to the total instruction count due to TextureLoad having side effects

UE - Rendering Architecture - Materials - Dec 4, 2024

When using materials with CustomData inputs, such as the Eye material with Iris Distance and Mask, Virtual Texture samples will increase the instruction count for each unique VTPageResult. Each cus ...